i created a html button in jsp using while loop i want to get the value of the specific button that was clicked but it shown result as undefined.
我不知道该怎么办，我也不可能是Java Script的新手。 请提前帮助我。
Blockquote 这是我尝试过的方法，但无法给未定义的结果
<td><button value="<%= path%>" onclick="myFunction()"><%= path %></button></td>
<script>
function myFunction() {
alert(this.value);
<% session.setAttribute("gurufile",path );%>
}
</script>
Blockquote 这是我的整个代码，我从数据库中获取按钮的值
<%@page import="java.util.ArrayList"%>
<%@page import="java.sql.Statement"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.ResultSet"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<%
out.println(request.getParameter("roll_no"));
%>
<h3 align="center" style="color:BROWN;"> Dr.A.P.J. Abdul Kalam Technical University, Uttar Pradesh, Lucknow</h3>
<h4 align="center" >( Formerly Uttar Pradesh Technical University )</h4>
<h4 align="center" style="color:blue;">AKTU-OneView</h4>
</br>
<hr align="center" style="color:lightgrey;">
<h3>Student Result</h3>
<%!
//golbally declear
String class_name=null;
String branch=null;
String rollno =null;
String path =null;
ArrayList a = new ArrayList();
int count =0;
%>
<%
//String roll_no = "1634010009";
String roll_no = request.getParameter("roll_no");
String url="jdbc:mysql://localhost/student_result";
String username="root";
String password="bilalminto";
String query="select * from new_student where roll_no='"+roll_no+"'";
System.out.println("rollno "+roll_no);
try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con=DriverManager.getConnection(url, username, password);
Statement st=con.createStatement();
ResultSet rs=st.executeQuery(query);
String student_name=null;
//String class_name=null;
//String branch=null;
//String rollno =null;
String father_name = null;
String mother_name = null;
if(rs.next()){
student_name=rs.getString("student_name");
class_name=rs.getString("class");
branch=rs.getString("branch");
rollno=rs.getString("roll_no");
father_name=rs.getString("fathers_name");
mother_name=rs.getString("mothers_name");
}
//Statement stm=con.createStatement();
//ResultSet rst=stm.executeQuery(query);
%>
<hr align="center" style="color:lightgrey;"></br>
<table width=100% border=1 cellspacing="0">
<tr align="left">
<td><b>Institute Code & Name :</b></td>
<td colspan="5"> (340) VIVEKANANDA COLLEGE OF TECHNOLOGY & MANAGEMENT, ALIGARH</td>
<td rowspan="5">print view</td>
</tr>
<tr>
<td><b>Course Code & Name:</b></td>
<td colspan="2"><%=class_name%></td>
<td ><b>Branch Code & Name</b></td>
<td colspan="2"><%=branch%></td>
<%
System.out.println("branch "+branch);
%>
</tr>
<tr>
<td><b>Roll No:</b></td>
<td colspan="2"><%=roll_no %></td>
<td><b>Enrollment No</b></td>
<td colspan="2">163401047822</td>
</tr>
<tr>
<td><b>Name:</b></td>
<td colspan="2"><%=student_name%></td>
<td><b>Mother Name</b></td>
<td> <%=mother_name%></td>
</tr>
<tr>
<td><b>Father's Name:</b></td>
<td colspan="2"><%=father_name%></td>
<td><b>Gender</b></td>
<td colspan="2">M</td>
</tr>
</table></br>
<%
}
catch(Exception e){
e.printStackTrace();
}
session.setAttribute("roll_no", roll_no);
%>
<hr align="center" style="color:lightgrey;">
<h3>One View Result</h3>
<hr align="center" style="color:lightgrey;">
<%
//String roll_no=session.getAttribute("roll_no").toString();
String query1 = "select distinct semester from subject where class_name='"+class_name+"' && branch='"+branch+"'";
try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con=DriverManager.getConnection(url, username, password);
Statement st=con.createStatement();
ResultSet rs=st.executeQuery(query1);
Statement st1 =con.createStatement();
ResultSet rs1 =null;
Statement st4 =con.createStatement();
ResultSet rs4 =null;
Statement st5 =con.createStatement();
ResultSet rs5 =null;
String semester =null;
String subject_code=null;
String subject_name=null;
String max_marks=null;
String marks_obtained = null;
//String path =null;
while(rs.next()){
semester=rs.getString("semester");
%>
<lable><b>Samester:</b></lable><label><%=semester%></label><lable><b>Total Subjects:</b></lable><label></label></br>
<lable><b>Total Marks:</b></lable><label>900</label><lable><b>Marks Obt:</b></lable><label>500</label></br>
</br>
<table width=100% border=1 cellspacing="0">
<tr>
<td><b>Code</b></td>
<td><b>Name</b></td>
<td><b>Max Marks</b></td>
<td><b>Marks Obtain</b></td>
<td><input type="text" name="" value="view copy"></td>
</tr>
<%
String query2 ="select * from subject where semester='"+semester+"'";
rs1=st1.executeQuery(query2);
while(rs1.next()){
subject_code=rs1.getString("subject_code");
subject_name=rs1.getString("subject_name");
max_marks=rs1.getString("max_marks");
String query3 ="select * from add_marks where roll_no='"+roll_no+"' and subject_code='"+subject_code+"'";
System.out.println(subject_code);
rs4 = st4.executeQuery(query3);
if(rs4.next() && rs4.getString("roll_no").equalsIgnoreCase(roll_no) && rs4.getString("subject_code").equalsIgnoreCase(subject_code)){
// if(rs4.next()){
marks_obtained=rs4.getString("marks_obtained");
path=rs4.getString("path");
}else{
marks_obtained = "Not Updated";
path = "Not Updated";
}
//session.setAttribute("gurufile",path );
a.add(count, path);
//out.println("pathof" +path);
%>
<tr>
<td><%=subject_code%></td>
<td><%=subject_name%></td>
<td><%=max_marks%></td>
<td><%=marks_obtained%></td>
<td><button value="<%= path%>" onclick="myFunction()"><%= path %></button></td>
</tr>
<%
count++;
}
%>
</table>
</br>
</br></br>
<%
}
%>
<%
}
catch(Exception e){
e.printStackTrace();
}
session.setAttribute("roll_no", roll_no);
%>
</body>
</html>
<script>
function myFunction() {
alert(this.value);
<% session.setAttribute("gurufile",path );%>
}
</script>
Blockquote或使用任何其他方法来获取被单击按钮的值
答案 0 :(得分：0)
您需要将this引用传递给该函数：
<button value="<%= path%>" onclick="myFunction(this)">
通过这种方式，您可以将单击按钮作为函数中的参数：
function myFunction(button) {
alert(button.value);
}